S000010827 [Member] Average Annual Total Returns	12 Months Ended	60 Months Ended	106 Months Ended	120 Months Ended	158 Months Ended	351 Months Ended
S000010827 [Member] Average Annual Total Returns	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2025
S&P SmallCap 600® Index (reflects no deductions for fees, expenses or taxes)
Prospectus [Line Items]
Average Annual Return, Percent	6.02%	7.31%		9.81%
Russell 3000® Index (reflects no deductions for fees, expenses or taxes)
Prospectus [Line Items]
Average Annual Return, Percent	17.15%	13.15%		14.29%
C000030056 [Member]
Prospectus [Line Items]
Average Annual Return, Percent	5.64%	6.81%		9.33%
Performance Inception Date						Oct. 15, 1996
C000030056 [Member] \| After Taxes on Distributions
Prospectus [Line Items]
Average Annual Return, Percent	2.53%	4.28%		7.15%
Performance Inception Date						Oct. 15, 1996
C000030056 [Member] \| After Taxes on Distributions and Sales
Prospectus [Line Items]
Average Annual Return, Percent	4.99%	5.05%		7.19%
Performance Inception Date						Oct. 15, 1996
C000030057 [Member]
Prospectus [Line Items]
Average Annual Return, Percent	5.90%	7.08%		9.60%
Performance Inception Date						Oct. 15, 1996
C000122595 [Member]
Prospectus [Line Items]
Average Annual Return, Percent	5.89%	7.07%		9.60%
Performance Inception Date					Nov. 08, 2012
C000173201 [Member]
Prospectus [Line Items]
Average Annual Return, Percent	5.88%	7.08%		9.57%
Performance Inception Date			Mar. 01, 2017